At the time of smoking, a main-stream smoke and a side stream smoke are generated from the tobacco. The main stream smoke passes through a cigarette and is inhaled by a smoker. The side stream smoke rises from the distal end of a lighted cigarette.
To reduce the amount of the side stream smoke, additives mentioned below have been added to the cigarette papers for a smoking article, as proposed below.
Jpn. Pat. Appln. KOKAI Publication No. 63-87967 discloses a package web for a smoking article having an outer peripheral surface area of about 8 m.sup.2 per m.sup.2 of a cigarette paper and containing an additive which contains an alkaline metal salt in an amount of about 15 wt %.
Jpn. Pat. Appln. KOKAI Publication No. 1-112974 discloses a smoking article rolled with paper containing an inorganic metal salt such as aluminium hydroxide or calcium hydroxide.
Jpn. Pat. Appln. KOKAI Publication No. 2-156877 discloses a smoking article rolled with cigarette paper containing calcium sulfate and calcium tartrate in an amount of 1 to 50 wt %.
Jpn. Pat. Appln. KOKAI Publication No. 3-43068 discloses a cigarette paper having a surface area of 20 to 80 m.sup.2 /g defined by a BET method and containing calcium carbonate (30 to 40%), a chemical burning agent (2 to 10%), monoammonium phosphate (0 to 1%) and sodium carboxymethyl cellulose (0 to 1%).
Jpn. Pat. Appln. KOKAI Publication No. 3-180597 discloses a cigarette paper containing calcium carbonate (30 wt %) having a surface area of 20 m.sup.2 /g or more and an organic acid (0.5 to 12 wt %) such as saccinic acid or malonic acid.
Jpn. Pat. Appln. KOKAI Publication No. 5-279994 discloses a cigarette paper containing secondary particles of calcium carbonate which are an aggregate of primary cubic-form particles of 0.15 .mu.m or less in diameter.
The conventional cigarette paper developed for reducing a side stream smoke can reduce the side stream smoke. However, it is significantly inferior in other requisite characteristics. For example, the cigarette must not go out even if a burning cigarette is allowed to stand alone and must burn at a desired rate. Such good burning characteristics are required.
The cigarette paper must have color and transparency satisfying a smoker's taste. Particularly, white is the most favorable color for the cigarette paper. It is desirable that the cigarette paper be as white as possible and low in transparency.
As is described above, the cigarette paper must be excellent not only in the effect of reducing the side stream smoke but also in all characteristics including optical characteristics of the cigarette paper and burning characteristics of the cigarette. More preferably, the ash of a cigarette left after burning must have an adhesive characteristic to, hold its shape and prevent scattering, and, must be white. The cigarette paper is desired to also have such ash characteristics mentioned above.
However, any of the aforementioned conventional techniques for reducing the side stream smoke has not yet succeeded in providing the cigarette paper excellent in all characteristics.
Not only a smoker but also non smokers around the smoker are made uncomfortable with the side stream smoke. Therefore, it is desired that the reduction of the side stream smoke be visually recognized even by the passive smokers. Hitherto, the reduction of the side stream smoke generated by smoking a cigarette has been studied. However, the reduction of the side stream smoke visually observed by the passive smokers has not yet been studied.